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enWed, 19 Dec 2018 10:03:33 GMTvBulletin60http://forums.mikeholt.com/images/misc/rss.pnghttp://forums.mikeholt.com/
Photocell output controlling contactor on another circuit.http://forums.mikeholt.com/showthread.php?t=195447&goto=newpost
Wed, 19 Dec 2018 03:40:04 GMTI have a 277vac circuit. It runs to a photocell that turns on some lighting.
The desire is to tie into the the output of the photocell to control a...I have a 277vac circuit. It runs to a photocell that turns on some lighting.
The desire is to tie into the the output of the photocell to control a contactor for a different lighting circuit in the same panel.
The idea seems strange to me but I can't think of any code violations. What say you?
]]>NECTwoskinsonemanhttp://forums.mikeholt.com/showthread.php?t=195447Transformer taphttp://forums.mikeholt.com/showthread.php?t=195443&goto=newpost
Tue, 18 Dec 2018 22:07:08 GMTI have two sets of secondary conductors from 75kva three phase 480v to 208/120v feeding two panels. Each panel main circuit breaker is 225A. So...I have two sets of secondary conductors from 75kva three phase 480v to 208/120v feeding two panels. Each panel main circuit breaker is 225A. So 225x2 = 450a which is 216% of transformer secondary full load amps.

The primary breaker is sized within 125% of full load amps.

Customer says transformer is protected by primary breaker. No need for secondary breakers at all in terms of transformer protection. The secondary breakers provided for secondary conductor and in accordance with tap rules. The secondary two sets feeding panels demand load is less than 75kva rating now.

The demand load of both panels is less than transformer 75kva rating at present but can exceed if in future they add load to panels to exceed that of the 75kva transformer since btoh panels have room and can add in future.

Is the above allowed in code?
]]>NEChhstinghttp://forums.mikeholt.com/showthread.php?t=195443Outpatient Emergency Receptalceshttp://forums.mikeholt.com/showthread.php?t=195439&goto=newpost
Tue, 18 Dec 2018 16:21:47 GMTPresently designing an outpatient facility with type B occupancy (2018 FGI guidelines apply) and the facility has a few procedure rooms. This...Presently designing an outpatient facility with type B occupancy (2018 FGI guidelines apply) and the facility has a few procedure rooms. This facility is not part of the hospital occupancy, but is physically connected to the hospital building. The 2014 NEC 517.10(B) states that outpatient facilities are not required to follow Part II - "Wiring and Protection" but I'm concerned not putting critical power receptacles at the patient bed locations.

Is it safe to assume an outpatient facility with type B occupancy would not follow any of Article 517, even though it is connected to the hospital?

Thanks!
]]>NECSDG0413http://forums.mikeholt.com/showthread.php?t=195439sub panel need a main breaker in multi unit building?http://forums.mikeholt.com/showthread.php?t=195426&goto=newpost
Tue, 18 Dec 2018 02:27:05 GMTI am wiring a new commercial steel building with 9 bays which could be 9 different tenants.
I have 9 meter sockets with 9 breakers on the outside...I am wiring a new commercial steel building with 9 bays which could be 9 different tenants.

I have 9 meter sockets with 9 breakers on the outside which feeds a panel on the inside of each unit.

Seeing that this is a feeder I should be able to use a MLO panel correct or is each unit considered a separate structure?
]]>NECSteviechia2http://forums.mikeholt.com/showthread.php?t=195426is this a legal emergency lock-out mechanism?http://forums.mikeholt.com/showthread.php?t=195424&goto=newpost
Mon, 17 Dec 2018 21:25:06 GMTHI all,
I've never seen this before. It appears to be a mechanical device for a manual emergency power transfer system that prevents the utility and generator breakers from being simultaneously closed. We found one instance where the transfer protocol was clearly labeled, but this particular building there was minimal labeling. Is it legal?

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]]>NECmalachi constanthttp://forums.mikeholt.com/showthread.php?t=195424Number of recepts on a 20A branch circuithttp://forums.mikeholt.com/showthread.php?t=195421&goto=newpost
Mon, 17 Dec 2018 20:15:40 GMTHi,
Trying to reconcile NEC 2008 210.21(B)(2) with 220.14(I), specifically Exhibit 220.4 which is in the 2008 Handbook. See attached for the two...Hi,

Trying to reconcile NEC 2008 210.21(B)(2) with 220.14(I), specifically Exhibit 220.4 which is in the 2008 Handbook. See attached for the two excerpts.

I had previously convinced myself that the maximum number of convenience outlets that could be on a single 20A branch circuit is 13. (180VA per outlet * 13 outlets = 2340VA, which is under 20A*120V=2400VA). This was under the assumption that the NEC prescribed load for convenience outlets already takes into account continuous vs non-continuous loading. Exhibit 220.4 also shows 13 outlets on a 20A branch circuit.

Now reading 210.21(B)(2) I'm not so sure. Has anybody else noticed this apparent contradiction? What's the actual max # of outlets on a 20A circuit?

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]]>NECshespuzzlinghttp://forums.mikeholt.com/showthread.php?t=195421Breaker Sizing for 200V motorhttp://forums.mikeholt.com/showthread.php?t=195419&goto=newpost
Mon, 17 Dec 2018 16:30:49 GMTI am trying to size a breaker for a 3-phase 200V air-compressor motor inside of a commercial device. The nameplate of the motor reads as follows
...I am trying to size a breaker for a 3-phase 200V air-compressor motor inside of a commercial device. The nameplate of the motor reads as follows

We are currently using a 13,13,10 breaker for the entire system , however we are experiencing widespread nuisance tripping.

The question we are trying to get to the bottom of is are we able to go up to a 15A breaker on this system. From the research I have done I have found out that for OVERLOAD protection, the cutoff is 125% FLA which is only 11.5A. The motor has built in thermal protection, but I haven't been able to find much information on thermal type N protection, so I do not know if it qualifies as adequate overload protection. From the information I found on Short-Circuit protection, the lowest rated standard breaker is 15A.

Any suggestions are appreciated. I'm a microcontroller guy so these standards are foreign to me.
]]>NECtaylorjtthttp://forums.mikeholt.com/showthread.php?t=195419EMT Installation at Finished Floorhttp://forums.mikeholt.com/showthread.php?t=195414&goto=newpost
Mon, 17 Dec 2018 12:26:58 GMTI have an installation where EMT has been installed at the finished floor. The location is indoors, but in a mechanical room where equipment can...I have an installation where EMT has been installed at the finished floor. The location is indoors, but in a mechanical room where equipment can theoretically be moved if necessary for maintenance. The location is dry, and no major lifting equipment (i.e. - fork truck traffic). However, looking at 358.12 (1) and being in proximity to the floor, I'm concerned about severe physical damage. The conduit contains control or low voltage power cable associated with a building automation system. Would I have an argument related to this installation?

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]]>NECmsimmshttp://forums.mikeholt.com/showthread.php?t=195414De-rating conductorshttp://forums.mikeholt.com/showthread.php?t=195411&goto=newpost
Mon, 17 Dec 2018 09:19:29 GMTI have 25 #10 XHHN in 1 1/4 EMT conduit. What is new rating of these wiresI have 25 #10 XHHN in 1 1/4 EMT conduit. What is new rating of these wires
]]>NECjbolenhttp://forums.mikeholt.com/showthread.php?t=195411When are you required to use grounding bushings?http://forums.mikeholt.com/showthread.php?t=195407&goto=newpost
Mon, 17 Dec 2018 03:23:01 GMTRunning rigid on a roof going into 24 x 24 can using locknut with gasket on both sides it's insulating the pipe from the can. I imagine this is one instance. What are others? Thank you for your help.
]]>NECzappyhttp://forums.mikeholt.com/showthread.php?t=195407Tapping a parallel feederhttp://forums.mikeholt.com/showthread.php?t=195403&goto=newpost
Sun, 16 Dec 2018 18:07:41 GMTNew to the forum, so I ask for your patience in advance. Hope I am in the right place, and that this question falls within the TOS guidelines.
We...New to the forum, so I ask for your patience in advance. Hope I am in the right place, and that this question falls within the TOS guidelines.
We have a 600 amp MDP with ancient breakers, and are adding a 200 amp panel for some mini-split A/C units. My intent is to install a 200 amp disconnect within 10 feet of the MDP, and use it to supply a w/p panel on the roof where the condensers will be located. The MDP is fed from a 600 amp main disconnect, in parallel. My question is, can this be accomplished by tapping one set of those parallel feeders in the MDP, or do the taps need to be in parallel as well? I hope my explanation is clear enough to be understood, and thank you in advance for your help.
]]>NECtnoble406http://forums.mikeholt.com/showthread.php?t=195403Fire Pump Feed From Meter Stackhttp://forums.mikeholt.com/showthread.php?t=195402&goto=newpost
Sun, 16 Dec 2018 17:55:18 GMTI have an interesting (or maybe common and not so interesting) scenario I could use some opinions on
Fire pump feed from a utility meter stack....I have an interesting (or maybe common and not so interesting) scenario I could use some opinions on

Fire pump feed from a utility meter stack. Power company wants fire pump feeder metered (of course) this is a small stack only 3 meters no main on the stack. 2 meters for tenants one for a fire pump. The 2 meters for the tenants will have a 200A breaker in the stack. The meter for the fire pump is interesting. First – we decided feeding the fire pump out of the stack is acceptable because there is no main in the stack and the feed comes from its own compartment within the stack keeping the feed separate from other sections. If we do not have a breaker in the stack for the fire pump doesn’t the feed for the fire pump become a feeder tap from the stack? The feed is less than 25’ so 25’ tap rule applies however;
The ampacity of the tap conductors must not be less than one-third the rating of the overcurrent device that protects the feeder.
There is no OCP protecting the feeder being tapped. This feeder would be the service conductors from the utility company’s transformer which feeds the stack.
The tap conductors terminate in a single circuit breaker, or set of fuses rated no more than the tap conductor ampacity in accordance with 310.15 [Table 310.15(B)(16)].
There is OCP in the fire pump controller so should be able to comply with this one by matching the feeder ampacity to the OCP.

Since the whole point of a fire pump feeder is to have nothing in its circuit which can interrupt the flow of electricity to it. Is it an issue to feed the fire pump from the stack without OCP even though it technically is a feeder tap from the stack which has no OCP. If the stack did have a main than we would need to tap ahead of the main anyway. In a nutshell any fire pump feed is going to be a tap which would not comply with the tap rule since it needs to be ahead of and not within the same enclosure as the main.
One really needs to think about this before responding as I have changed my mind several times as to what I would allow.
]]>NECLibertyEngineeringhttp://forums.mikeholt.com/showthread.php?t=195402Motor Thermal Overloadshttp://forums.mikeholt.com/showthread.php?t=195400&goto=newpost
Sun, 16 Dec 2018 17:12:43 GMTHave never come across motor switches located remotely on a wall like this. They seem to be showing regular toggle type switches and not thermal...Have never come across motor switches located remotely on a wall like this. They seem to be showing regular toggle type switches and not thermal overload type for the exhaust fans. As you can see in the other pic for another motor type they do show overload type. The only thing I can think of is the exhaust fan has some sort of means of disconnect internally( they don't show anything). Can they exhaust fan switches be regular toggle type as they show and not thermal overload type? Thanks.

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]]>NECmstrlucky74http://forums.mikeholt.com/showthread.php?t=195400soda coolerhttp://forums.mikeholt.com/showthread.php?t=195386&goto=newpost
Sat, 15 Dec 2018 01:21:32 GMTsoda cooler in restaurant lobby qhere customer come to order and not within six feet of sink and not in Kitchen. Does the soda cooler receptacle...soda cooler in restaurant lobby qhere customer come to order and not within six feet of sink and not in Kitchen. Does the soda cooler receptacle required to be on gfci?

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]]>NEChhstinghttp://forums.mikeholt.com/showthread.php?t=195386Industrial Design basic questionhttp://forums.mikeholt.com/showthread.php?t=195379&goto=newpost
Fri, 14 Dec 2018 17:26:04 GMTA friend of mine owns a machine shop. They are moving to a smaller space that only has 400a 3Phase (existing is 800a). They are getting rid of some...A friend of mine owns a machine shop. They are moving to a smaller space that only has 400a 3Phase (existing is 800a). They are getting rid of some equipment but are still concerned that they will not have power to meet code calculations. I was thinking that they could put two pieces of equipment that are never needed at the same time onto contactors controlled by a 3-way switch so that only one piece of equipment could have power at one time. Does anyone know if this is satisfactory for load calculation purposes? We mostly do resi.